The present invention refers to plastic handles for cutting instruments such as scissors and to scissors using such handles.
It is known to manufacture scissors having steel blade members and plastic handles, for example from Brazilian patent 86447. It is also known, for example from Brazilian Utility Model patent 5500563 of Jun. 10, 1975 for dress makers scissors to have the plastic handles anatomically shaped to receive the user""s fingers so as to maximise comfort and cutting control. Comfort in using the scissors depends not only on the shape but also on the extension of the surfaces of the finger-receiving holes that are contacted by the user""s fingers since the sensation of effort in cutting is reduced as the area of finger contact is increased. For this reason and bearing in mind that it does not result in any appreciable increase in weight of the scissors, plastic handles may be made with shapes and sizes that are more comfortable to use and give the sensation of lightness in cutting even thick cloth.
It has been found, however, that perfect adaptability of the handles by varying their shapes and dimensions is not in practice possible due to the very variable characteristics of the hands of different individuals. An extreme example is the obvious difference between right-handed and left-handed persons.
The work xe2x80x9cThe Psychology of Everyday Thingsxe2x80x9d by Donald A. Norman states: xe2x80x9cIn this case only special products help, such as scissors and knives for left-handed persons. But these special instruments sometimes do not work, for example when the same item has to be used by many different people. In such cases, the only solution is to make it ambidextrous, even if this makes it a little less efficient for each person in particularxe2x80x9d.
U.S. Pat. No. 4,091,539 to Tokuji Watanabe issued on May 30, 1978 discloses large size scissors without plastic handles but rather of a simple nature with each blade or cutting member formed with a finger-hanging hole portion by press moulding, such hole portion having then applied thereto an anatomically shaped plastic part. That patent shows how such specially shaped parts may be simply applied to the inner peripheries of the holes in the finger-hanging hole portions so as to provide inexpensive decorative large size scissors with inner protective rings in the finger holes. However, it is clearly shown that the scissors cannot be adapted for use by left-handed persons, such alternative scissors having a mirror image construction both as regards the cutting members and as regards the protective rings.
The solution of Watanabe, however, apart from not being applicable to scissors already manufactured with the larger more comfortable plastic handles, does not in any way solve the problems of variations in the characteristics of the hands of different right-handed or different left-handed people.
Other totally metallic scissors are known in which the finger holes are covered with rigid or soft plastic rings injected directly onto the metal parts or applied thereto mechanically. Examples are the products INCOLMA of Columbia (based on the product WOW ALEX of Japan), HUMMINGBIRD-PLUS of Japan, xe2x80x9cPANDAxe2x80x9d AMC of France, SHEFFIELD of the United Kingdom and H. W. Bxc3x96KER of SOLINGEN (Germany).
Other types of scissors are known that plastic handles the xe2x80x9ceyesxe2x80x9d or finger holes of which are provided with hard plastic rings of different colours. Such an arrangement has a purely aesthetic purpose, an example being the product commercialised as BARRILITI by the company SOLINGEM of Germany.
Another inconvenience to be found in all known large size scissors having plastic handles and designed to be adapted specially to the hand (ergometrically designed scissors) is that, due to the bulkiness of the handles and the ergometrically formed portions of the finger holes, there is no well defined longitudinal plane of symmetry of each handle and, to the extent that such plane of symmetry could exist, it does not coincide with the cutting plane of the blade members. This makes cutting control difficult. An example can be found in the scissors commercialised by FISKARS.
A first object of the present invention is to provide a plastic handle for a cutting instrument such as scissors that automatically adjusts itself to the hand of the user, independently of the size of the hand or of whether he is right- or left-handed.
The present invention thus refers to a plastic handle for a cutting instrument such as scissors, comprising a shank portion having a first blade end adapted for receiving substantially longitudinally therein a handle end of a cutting member and a second finger-receiving end, and a finger-receiving portion in continuation to the second end of the shank portion and having an external peripheral surface and an internal peripheral surface, the internal peripheral surface defining a finger hole for receiving one or more fingers of the user.
According to the invention, such a plastic handle is characterised by further comprising an elastically deformable annular covering applied around the internal peripheral surface of the finger-receiving portion so as to provide the latter with ergometric characteristics adaptable to any finger, independently of the user being right- or left-handed.
It is particularly advantageous and possible in accordance with this invention for the plastic handle to have a longitudinal plane of symmetry.
Preferably, the elastically deformable annular covering comprises a separate part attached to said internal peripheral surface of the finger-receiving portion and, in a preferred embodiment, such annular covering or ring has an inner peripheral surface for finger contact and an outer peripheral surface shaped to cooperate in mutual connecting relationship with the shaped internal peripheral surface of the finger-receiving portion.
In such preferred embodiment, one of the above mentioned internal and outer shaped peripheral surfaces is shaped to form a continuous T-shaped rib, the other of such surfaces being shaped to define a corresponding cooperating continuous T-shaped channel.
In order to avoid discomfort due to contact between the user""s finger and a relatively sharp edge of the internal peripheral surface of the finger-receiving portion, the inner peripheral surface of the ring is preferably rounded and wider than both of the internal and external peripheral surfaces of the finger-receiving portion.
The elastically deformable ergometric covering or ring permits the inner periphery of the finger-receiving portion of the handle to adapt itself to the shape and angle of the finger or fingers, providing a cushioning effect without, however, removing the firm sensation of the rigid plastic of the finger-receiving portion. Such elastically deformable covering or ring may comprise natural rubber or synthetic materials, such as thermoplastic rubbers, thermoplastic elastomers, thermoplastic polyester elastomers or thermoplastic polyurethane elastomers. The covering or ring may be the same colour as that of the rigid plastic of the main part of the handle or may be differently coloured so as to make it stand out and emphasise its special function.
The invention also relates to scissors of the type comprising first and second cutting members, each having a blade portion and a handle end portion, the cutting members being pivoted together to permit relative scissor movements thereof about a point between the blade portions and the handle end portions. According to the invention, scissors of this type are provided with first and second plastic handles respectively mounted on the handle end portions, each handle being as defined above and having the mentioned elastically deformable annular covering around the finger holes.
As will be better understood from the following specific description to be made with reference to the accompanying drawings, a cutting instrument or scissors incorporating the above characteristics has the following desirable characteristics:
the elastically deformable rings provide the instrument with an automatic adaptability to the shapes and dimensions of the fingers of the specific user as opposed to what happens with known xe2x80x9cergometrically designedxe2x80x9d scissors which provide substantially fixed finger-receiving shapes to which the fingers of the user are expected to adapt themselves;
the elastically deformable rings reduce the feeling of effort in cutting since finger pressure is applied to a deformable surface;
abrasion of the skin due to direct contact between the user""s fingers and the surface of the hard plastic, particularly because of the mould lines and any consequent moulding burrs, is avoided; and
firmer and more controlled handling of the instrument due to the anti-slip properties of the elastic rings in the finger holes as well as to the fact that the handles have planes of symmetry coincident with the cutting plane of the cutting blades or members.